I know it's heresy these days, but given the I/O throughput you're looking for
and the amount you're going to spend on disks, a T5-2 could make sense when
they're released (I think) later this month.
Crucial sells RAM they guarantee for use in SPARC T-series, and since you're at
an edu the academic discount is 35%. So A T4-2 with 512GB RAM could be had
for under $35K shortly after release, 4-5 months before the E5 Xeon was
released. It seemed a surprisingly good deal to me.
The T5-2 has 32x3.6GHz cores, 256 threads and ~150GB/s aggregate memory
bandwidth. In my testing a T4-1 can compete with a 12-core E-5 box on I/O and
memory bandwidth, and this thing is about 5 times bigger than the T4-1. It
should have at least 10 PCIe's and will take 32 DIMMs minimum, maybe 64. And
is likely to cost you less than $50K with aftermarket RAM.
-- Trey
On Mar 15, 2013, at 10:35 PM, Marion Hakanson <hakan...@ohsu.edu> wrote:
>>> Ray said:
>>>> Using a Dell R720 head unit, plus a bunch of Dell MD1200 JBODs dual pathed
>>>> to a couple of LSI SAS switches.
>> Marion said:
>>> How many HBA's in the R720?
> Ray said:
>> We have qty 2 LSI SAS 9201-16e HBA's (Dell resold[1]).
>
> Sounds similar in approach to the Aberdeen product another sender referred to,
> with SAS switch layout:
> http://www.aberdeeninc.com/images/1-up-petarack2.jpg
>
> One concern I had is that I compared our SuperMicro JBOD with 40x 4TB drives
> in it, connected via a dual-port LSI SAS 9200-8e HBA, to the same pool layout
> on a 40-slot server with 40x SATA drives in it. But the server uses n
> expanders, instead using SAS-to-SATA octopus cables to connect the drives
> directly to three internal SAS HBA's (2x 9201-16i's, 1x 9211-8i).
>
> What I found was that the internal pool was significantly faster for both
> sequential and random I/O than the pool on the external JBOD.
>
> My conclusion was that I would not want to exceed ~48 drives on a single
> 8-port SAS HBA. So I thought that running the I/O of all your hundreds
> of drives through only two HBA's would be a bottleneck.
>
> LSI's specs say 4800MBytes/sec for an 8-port SAS HBA, but 4000MBytes/sec
> for that card in an x8 PCIe-2.0 slot. Sure, the newer 9207-8e is rated
> at 8000MBytes/sec in an x8 PCIe-3.0 slot, but it still has only the same
> 8 SAS ports going at 4800MBytes/sec.
>
> Yes, I know the disks probably can't go that fast. But in my tests
> above, the internal 40-disk pool measures 2000MBytes/sec sequential
> reads and writes, while the external 40-disk JBOD measures at 1500
> to 1700 MBytes/sec. Not a lot slower, but significantly slower, so
> I do think the number of HBA's makes a difference.
>
> At the moment, I'm leaning toward piling six, eight, or ten HBA's into
> a server, preferably one with dual IOH's (thus two PCIe busses), and
> connecting dual-path JBOD's in that manner.
>
> I hadn't looked into SAS switches much, but they do look more reliable
> than daisy-chaining a bunch of JBOD's together. I just haven't seen
> how to get more bandwidth through them to a single host.
>
> Regards,
>
> Marion
>
>
>
>
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